RES 2025054 - Laserfiche WebLink

Vegetation and Development Within WUI Area 2 Open -canopy oak woodlands and grasslands characterize the vegetation in WUI Area 2 along the City's south and southeast sides. Areas of continuous grassland are common throughout this WUI area. Tree cover is varied, with most areas only having scattered trees within the grasslands. Sheltered areas like drainage bottoms and north - facing slopes generally have denser tree cover. Development in this WUI area is composed of larger planned residential communities with a higher density (less than 30 feet between homes) than the communities along Foothill Road. Vegetation within these communities is predominantly maintained ornamental landscaping. Natural vegetation is limited to isolated strips of vegetation along drainage bottoms or small sections of hillside. The exception to this are the homes along the southern limit of development. These areas have more in common with the communities along Foothill Road and contain ornamental landscaping near the homes and natural areas around the perimeter of the landscaped areas. Tree -Related Fire Hazards Public Trees Public trees within the WUI areas of the City are comprised of trees located along roadways, trees in open space areas, and park trees. Most of the public trees in WUI areas in Pleasanton are located within the more than 700 acres of open space in the City. Because these trees are further than 100 feet from a structure or 20 feet from a road and are outside of the defensible space area in the LPFD's vegetation management standard, the City does not regularly maintain them. The public trees thatthe City does maintain within the WUI areas are predominantly located along roadways, with a minor component in City parks. Many native and ornamental tree species present along roadways in the WUI areas are broadleaf trees that do not have characteristics identified by state or local fire agencies as highly flammable. Native Oak (e.g., coast live oak and valley oak) and common landscape tree species (e.g., ornamental pear and sweetgum) are identified as 'fire resistant' or have a 'favorable fire rating' according to state and local wildfire preparedness guides. SubAppendixA contains a list of references for fire-resistant species and fire -wise landscaping. Dead Public Trees and Removals Dead trees are a fire hazard. While live trees often contain a large amount of water in their tissues, dead tree tissues, particularly the leaves and small branches, have moisture levels that are generally in equilibrium with the moisture in the air. As a result, they are readily ignited and can burn under conditions where green vegetation would not. Most significantly concerning are recently dead trees with a full crown of dead leaves or needles since these dead leaves readily ignite, spreading fire into the tree crown and producing many embers. Dead public trees are a transitory phenomenon because these trees are likely to fall into a public right of way or park and the City makes removing these trees a priority. For this reason, the number of dead trees in the City changes annually, but they are always a minor component of the City's trees. At the time of the inventory, dead trees comprised 0.5% of City trees and the City removes roughly 225 dead trees per year. Public Tree Maintenance Maintenance of individual trees and groups of trees is as important as tree species or characteristics. Well-maintained trees, with minimal deadwood or leaf litter accumulation and adequate clearance between the crown and surface vegetation, are less likely to ignite and burn. The City works with a contractor to carry out grid pruning of street trees every five years and regularly maintains public trees for safety and clearance above roadways and sidewalks (pers comms G. Damonte July 2023), so public trees are generally maintained in a condition that reduces the risk of fire spreading into the tree crowns. APPENDIX A -WILDFIRE 13 of 219